M058SFAN Datasheet, PDF (38/72 Pages) List of Unclassifed Manufacturers – 32-bit Microcontroller

NuMicro M058S Series Datasheet
6.3.4 Power-down Mode Clock
When chip enters Power-down mode, system clocks, some clock sources, and some peripheral
clocks will be disabled. Some clock sources and peripherals clocks are still active in Power-down
mode.
The clocks still kept active are listed below:
 Clock Generator
 10 kHz internal low speed oscillator clock
 Peripherals Clock (when 10 kHz low speed oscillator is adopted as clock source)
6.3.5 Frequency Divider Output
This device is equipped with a power-of-2 frequency divider which is composed by 16 chained
divide-by-2 shift registers. One of the 16 shift register outputs selected by a sixteen to one
multiplexer is reflected to the CKO pin. Therefore there are 16 options of power-of-2 divided
clocks with the frequency from F_in/2¹ to F_in/2¹⁶ where Fin is input clock frequency to the clock
divider.
The output formula is F_out = F_in/2^(N+1), where F_in is the input clock frequency, F_out is the clock
divider output frequency and N is the 4-bit value in FREQDIV.FSEL[3:0].
When write 1 to DIVIDER_EN (FRQDIV[4]), the chained counter starts to count. When write 0 to
DIVIDER_EN (FRQDIV[4]), the chained counter continuously runs till divided clock reaches low
state and stay in low state.
If DIVIDER1(FRQDIV[5]) set to 1, the frequency divider clock (FRQDIV_CLK) will bypass power-
of-2 frequency divider. The frequency divider clock will be output to CKO pin directly.
22.1184 MHz
HIRC
11
HCLK
10
10 kHz LIRC
01
4~24 MHz HXT
00
FRQDIV_S (CLKSEL2[3:2])
FDIV_EN (APBCLK[6])
FRQDIV_CLK
Legend:
HXT = 4~24 MHz external high speed crystal oscillator
HIRC = 22.1184 MHz internal high speed RC oscillator
LIRC = 10 kHz internal low speed RC oscillator
Figure 6.3-6 Clock Source of Frequency Divider
Nov. 27, 2014
Page 38 of 72
Rev.1.03